2. Cellular respiration and ATP synthesis Flashcards
All living cells, and therefore all living organisms,
need
energy in order to survive
Energy is required for many different purposes. Every living cell, for example, must be able to move substances across its membranes against their concentration gradients, by
active transport
active transport is
Energy-requiring process that moves material across a cell membrane against a concentration difference
Cells need to use energy to drive many of their metabolic reactions, such as (3)
- chemical synthesis of substances,
- growth and division of cells,
- active transport of substances into and out of cells,
- electrical transmission of nerve impulses,
- mechanical contraction of muscle (movement)
Cells obtain energy by metabolic pathways known as
respiration
Respiration is
The process by which cells break down simple food molecules to release the energy they contain.
Respiration releases
chemical potential energy from glucose and other energy containing organic molecules
Cellular respiration is the
chemical breakdown of organic molecules that occurs inside all living cells.
the transfer of chemical energy from organic molecules so that it is available for cells in a useable form known as ATP
Do not confuse it with breathing
The organic molecules is oxidised during cellular respiration in order that
that energy is made available for ATP synthesis
what is a short-term store of energy
Carbohydrates
what is a long-term store of energy
fats
Protein may be used as a source of energy if
present in larger quantities than required for growth, repair and replacement
Carnivores respire more protein in their diet than herbivores because
their diet consists mostly of meat.
Respiratory substrates (3)
Carbohydrates
fats/lipids
proteins
how much energy each respiratory substrate releases
Carbohydrates 16kJg –1
fats/lipids 39 Jg –1
proteins 17Jg –1
ATP stands for
adenosine triphosphate
Every living cell uses ATP as its
immediate source of energy
When energy is released from glucose or other molecules during respiration, it is used to make
ATP
diagram showing the structure of an ATP molecule
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ATP is what type of molecule?
phosphorylated nucleotide
ATP is similar in structure to
the nucleotides that make up RNA and DNA
ATP molecules contain
energy
What happens when one phosphate group is removed from each molecule in one mole of ATP
30.5kJ of energy is released
what type of reaction is it when one phosphate group is removed from each molecule in one mole of ATP an energy is released
a hydrolysis reaction, and
it is catalysed by enzymes called ATPases
Most cells contain many different types of ATPases
The products of the reaction of the hydrolysis of ATP are
ADP (adenosine diphosphate) and a phosphate group (Pi ).
ATP + H20 ↔ ADP + Pi
30.5kJ released
More energy can be obtained from the hydrolysis of ATP if
a second phosphate group is removed
ADP + H20 ↔ AMP + Pi
30.5kJ released
The each-way arrows in these equations mean that the reaction can go either way
AMP stands for
adenosine monophosphate
ATPases may catalyse the
synthesis of ATP, or its breakdown
ATP is used for
almost every energy-demanding activity in the body
The amount of energy contained in one ATP molecule is often a suitable quantity to use for a particular purpose.
why is a ATP molecule better to use than a glucose molecule
One glucose molecule would contain too much, so a lot would be wasted if all the energy in a glucose molecule was released to make a particular event happen
Why is ATP useful to cells?
ATP can provide energy in small packages.
Also, the energy in ATP can be released very quickly and easily, at exactly the right time and in exactly the right place in a cell, just when and where it is needed.
ATP is often known as
the ‘energy currency’ of a cell.
Each cell has to make its own ATP because it
cannot be transported from one cell to another
However, within a cell ATP can be likened to money – a kind of energy currency – that can be used to provide energy for a wide range of processes
the four components of Cellular respiration are
glycolysis,
Krebs cycle
electron transport chain and
oxidative phosphorylation
These pathways of cellular respiration (glycolysis, Krebs cycle, electron transport chain and oxidative phosphorylation) allow
the energy within the glucose molecule to be released at a controlled rate so that ATP can be produced gradually.
what happens to the energy produced in the energy conversion in the body
The stepwise breakdown of glucose to carbon dioxide and water gives a yield of 36–38 ATP molecules, depending on the conditions.
Approximately 39 % of the energy that is stored in glucose is converted to the energy within the ATP molecules while the remainder is lost as heat.
This energy conversion in the body is more efficient than the conversion of energy in gasoline into movement of a car – only 25 % of gasoline energy is converted and the rest just makes the car engine hot
The stepwise breakdown of glucose to carbon dioxide and water gives a yield of
36–38 ATP molecules, depending on the conditions.
Approximately 39 % of the energy that is stored in glucose is
converted to the energy within the ATP molecules while the remainder is lost as heat
Aerobic refers to
any process that needs oxygen to occur
Anaerobic refers to
any process that can occur without oxygen.
Anaerobic can also refer to the metabolism of an organism that can live without oxygen
Aerobic respiration is the
complete breakdown of sugar or other organic compounds (e.g. fat and proteins) to carbon dioxide and water, to release energy.
The complete oxidative breakdown of glucose is called
respiration
what is the organelles in which respiration occurs
The mitochondria
Glycolysis occurs in the
in the cytosol or cytoplasm of the cell
Adenosine Triphosphate (ATP) is made from what three components?
- Ribose (the same sugar that forms the basis of DNA).
- A base (a group consisting of linked rings of carbon and nitrogen atoms); in this case the base is adenine.
- Up to 3 phosphate groups. These phosphates are the key to the activity of ATP
Figure 13.1 Overview of the oxidation of glucose
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Cellular respiration is the process that includes
all the metabolic reactions needed to break down sugar and other organic compounds and generate ATP
Cellular respiration requires what?
oxygen
Cellular respiration generates what?
ATP and carbon dioxide
In other words, cellular respiration and aerobic respiration are
different terms for the same process
what is a source of energy in both aerobic and anaerobic conditions
Glucose
The maximum energy yield for the oxidation of glucose is achieved how?
under aerobic conditions and some of the energy released from glucose is captured in the form of high-energy bonds in ATP.
The energy that is not captured in ATP is dissipated as heat.
In cellular respiration, glucose is oxidised to
carbon dioxide and water
cellular respiration is what type of reaction?
respiration releases energy – it is an exergonic reaction
which are high and low energy molecules in glucose and its oxidation products?
Glucose is a high-energy molecule and
its oxidation products (carbon dioxide and water) are low-energy molecules
The energy used in all cellular reactions comes from ATP. By breaking the 3rd phosphate from the ATP molecule what happens?
energy is released, which can be used to power intracellular reactions
Oxidation is
the loss of electrons
reduction is
the gain of electrons
The overall equation for the complete oxidation of glucose is
C6H12O6 + 6O2 → 6CO2 + 6H2O + energy
the first group of reactions that takes place in respiration
Glycolysis
example of recycling of ATP in cells in running
a runner uses 84kg of ATP in a marathon (more than their total body weight),
yet there are only 50g of ATP in the entire body
This means each that each molecule of ATP has been recycled 1676 times during the race!
Normally, as soon as ATP has been converted into ADP + Pi it is converted back into ATP using energy from respiration. However, during exercise
ADP may be converted into AMP or even Adenosine to provide energy
Diagram of How the energy in ATP is liberated:
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why is ATP used as an immediate source of energy in cells instead of glucose?
glucose cannot be used directly by cells as a source of energy because a glucose molecule would contain far too much energy, so a lot would be wasted if cells used glucose molecules as their immediate source of energy
the hydrolysis of one ATP molecule releases a small ‘packet’ of energy that is often just the right size to fuel a particular step in a process.
The formation of ATP from the break down of glucose takes place during
cellular respiration
Anaerobic respiration takes place in the absence of oxygen and produces what?
lactate (in animals) or ethanol and carbon dioxide (in plants and fungi) bur only a little ATP in both cases
both aerobic and anaerobic respiration produces ATP but
anaerobic respiration produces less
both aerobic and anaerobic respiration start with the process of
glycolysis but the stages after glycolysis differ
Energy is
the capacity to do work
Respiratory quotient is
The ratio of the volume of carbon dioxide given off to the volume of oxygen used up over the same time period during respiration
Energy is stored within cells as
chemical energy
This is also the most appropriate form in which it can be transferred efficiently from cell to cell and released in regulated amounts as, and when, required
Energy in living organisms is derived from….
the sun
what is the major respiratory substrate in respiration and during aerobic respiration it undergoes a series of enzyme-controlled oxidation reactions
glucose
equation of cellular respiration
C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP
why are the ATP molecules in a cell are constantly being cycled between ATP and ADP + Pi
All the processes in a cell that require energy (such as muscle contraction, active transport and biosynthesis) use ATP to provide that energy.
So these processes all involve ATPase enzymes, which catalyse the breakdown of ATP to ADP + Pi, and make use of the energy released
So the ATP molecules in a cell are constantly being cycled between ATP and ADP + Pi:
respiration does not “produce” or “make” energy because
the energy is already there in the glucose molecule
the coenzymes involved in respiration are
NAD
FAD
coenzyme A.
a coenzyme is a
a molecule required for an enzyme to be able to catalyse a reaction
during respiration NAD and FAD are..
reduced
The term ‘reduce’ means to add hydrogen, so reduced NAD has had hydrogen added to it
the term ‘reduced’ means to
add hydrogen
Without the presence of NAD or FAD to accept the hydrogen what would happen?
the dehydrogenase enzymes involved in respiration would not be able to remove hydrogen from their substrates
